Automatic telephone system.



H. G. WEBSTER.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED FEB. 27, 1907.

1,169,894 Patented Feb. 1, 1916.

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AUTOMATIC TELEPHONE SYSTEM.

AFPLICATIQN .HLED FEBvZT, 1907.

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AUTOMATlC TELEPHONE SYSTEM.

APPLICATION FILED FEB. 27) 1907.

1,169,894. Pam Bea Feb; 1, 1916.

5 SHEETS-SHEET 3 H. G. WEBSTER.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED FEB. 27, 1907.

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APPLIQATION FILED FEB. 27. I907- 1 169,894, Patented Feb. 1, 1916.

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PBUCATIUN FILED FEB. 27, I901- H. G.-WEBSTER. 1 n

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AUTGMATIC TELEPHGZIE To aZZ whom it may concern:

Be it known that I, HARRY G. WEBSTER, a citizen of the United States, residing in Chicago, in the county of Cook, State of Illinois, have invented new and useful ll provements in Automatic Telephone Systoms, of which the following is a specification.

My invention relates to automatic telephone systems in which a central source of current is. employed for operating the switches and for purposes of conversation, and in which the selective switching mechanisms, employed in establishing the connections between the calling and the called lines, are provided in numbers proportioned to the numbers of expected co-existing conversations, there being no selective switching mechanisms individual to subscriberslines.

The general object of my invention is to provide improved circuit structures operating in connection with simplified mechanical switches, there being features of novelty and utility both in the said structures and the mechanical switches, the inveiition of the two having gone hand in hand and being mutually dependent and contributing to pro duce' a single result.

In accordance wlth my inventlon, the subscrlhers lines are provided at the exchange ivith multiple terminals of two difierent the lines by means of said contacts as calling lines in order .to place the directively operated step-by-step central ofiice switches under the control of the substation calling devices of the calling lines. The line selectors are preferably not constantly operating mechanism but are normally at rest, the telephone lines having associated with them mechanisms operative, when calls are initiated over the lines, to distributively start into operation the line selectors. One such selector is started for each initiated call and when started, automatically seeks out and connects with contacts of the calling line.

I am aware that systems have heretofore been proposed embodying certain of the features above outlined. The structure of my $pectfication of Letters l st-eat.

Application filed February 27, 1953?.

Q Patented Feb. ll, react Serial No. 859,625.

1 *2 e 1' 1 invention, nowever, cutters among other respects from these in that i do awa with special apparatus apart from the line selectors and line circuits for starting line selectors, the arrangement of my structure being such that normally a slngle line see lector is operatively associated with. the lines which it serves; as soon as the {first switch is started, an oil-normal contact is operated to extend the common starting circuit past the started switch to the next switch of the group, which latter switch is placed under the control of the line circuits of the group of lines which switches serve as soon as the first switch has completed its selection of the calling line.

Another feature of novelty found in my invention consists in the manner in which, after the calling subscriber has caused the operation of a first selector to pick the thousand wanted, the call is extended to the connector of the hundred wanted out of the s lected thousand. The first selectors and line selectors are linked together in permanently associated pairs, one switch of a pair, the line selector, operating to select the calling line as before indicated. The other switch of the pair has before it, arranged in groups, contact sets for each thousand in the exchange (assuming a ten thousand exchange), a first selector, after it is by the operation of the line selector placed in connection with the calling line, being directively operated from the substation to select the group of contacts representing the wanted thousand and then automatically operated to select the first idle contacts out of the said group. In the structure of my invention, the contact sets at the first selectors are not connected to second selector-s having active terminals for selecting group contacts and then the idle contacts, but the said contacts at the first selector banks are connected to conductors eeltending to, and appearing before the contact wipers of automatically operated trunk selecting switches, each trunk selecting switch being permanently connected to a connector adapted to select terminal contacts oi any line out of Y a particular hundred to which the connector is assigned. The contacts appearing in the banks of the selectors are stationary contacts, and the wires connected to them extend to stationary contacts disposed in the banks of the trunk selecting switches. It

the usual ten per cent. ratio of trunking is preserved, there will be ten connectors for each hundred lines, and consequently ten trunk selecting switches, each joined to a connector, for each hundred, making for the thousand,'ten groups of switch pairs of ten pairs each. Each contact set at a first selector pertaining to a particular one thousand, will, in such case, have its conductors multipled one hundred times, once at each trunk selecting switch of the one thousand. Included in the mechanisn'i of the trunkcircuit connecting the stationary contacts of the first selector with the stationary contacts at the trunk selectors of the connectors of the thousand is a simple directively operated selective switch. The bank contacts at the trunk selecting switches are normally uns'electable in character, the private contacts being connected to ground through the mechanism of the simple switch before mentioned. After the calling subscriber has extended his line, by the operation of a first selector to an idle trunk-circuit appropriated to the desired one thousand, he operates the switch of the trunk-circuit around to a position corresponding with the wanted one hundred of the thousand, the bank contacts of the trunk-circuit continuing in their unselectable condition. An impulse succeeding the directive impulses then operates to remove the ground from the private contacts of the selected trunk-circuit appearing in the banks of the trunk selecting switches ertaining to the wanted one hundred, while leaving the bank contacts of the trunk selecting switches of the nine other hundreds of the thousand in their busy or unselectable condition. The said impulse also operates to start an idle trunloselecting switch of the group of the corresponding hundred which then automatically proceeds in its operation to select and connect with its particular bank contacts of. the trunk-circuit which have been rendered selectable, as before described. Since the sets of bank contacts of the trunkcircuit at the trunk selectors of the other.

hundreds of the thousand have been left unselectable, as before described, any trunk selecting swltch of the other hundreds winch may be started by some other calling subscriber, in putting through his call, will be unable to connect with the trunk-circuit in question, and no interference or improper selection'can arise. of trunking, including .a selective switch controlling group-wise the private multiples of a trunk-circuit, and being adapted selectively and under control of substation of one hundred lines to mechanism to render one group of such terminals selectable while maintaining the others excluded from being selected or busy, to be novel. Its utility will be apparent from the consideration that it will permit a group which a large 1. Figs. 1 and 5 I believe this method amount of incoming, business goes to be provided with more than the usual ten connectors, without requiring for the purpose second selectors to beprovided having more than the usual ten sets of contacts to a level or without requiring an especial distribution of the stationary multiple contacts of the connectors for the hundred at the second selectors the arran ement last indicated con 7 h hundrcd wanted unless receiving the busy signal he were to hang up his receiver and on the second trial succeed .in reaching a second selector having before it multiple contacts of the other ten connectors for the wanted hundred. In accordance with the structure of my invention, however, if twenty connectors were to be provided for a particular hundred, a trunk selector would be provided for each such connector, and

each trunk-selectorcould be started from any; trunk-circuit of the thousand and could connect any calling line through to its connector without rendering it necessary for the subscriber to hang up hisreceiver and make a call twice. These and other features of my invention will be more readily understood from the consideration of the drawings in which Figure 1 illustrates circuits of a 10.000 line system embodying my invention. Figs. 2 and 3 are respectively side and front cicvations of the switch for the circuit of Fig. illustrate the off-normal combinations of said switch. Figs. (3 and 7 show respectively the rotary actuating mechanism and the rotary restoring spring arrangement of said switch. l igs. 8 and 0 are respectively top and side views of the trunk switch of the circuit at l) in Fig. 1, Fig. 10 its olf-normal combination and Fig. 11, a schematic view of the contacts of said switch and their multiplinm Fig. 11 also illustrates schematically a trunk arrange ment forthe system of Fig. 1. Fig. 12 is a diagram indicating a trunking arrangemen for Fig. 1.

Referring first to Fig. 1 comprising Sheets 1, 2 and 3, I show at A and II two subscribers: stations connected with the exchange by limbs L-L of their respective telephone lines, which are provided with be. selected by connectors when the lines are messes em loyed as called lines, and with-the further multiple terminals 35--3637 adapted to beselected by line selectors whenthe lines are employed as calling lines. 'Assuming a 5 ten thousand line exchange, the subscriberslines are preferably divided into groups of one hundred as called lines and as calling lines, their grouping as called lines being in conformity with the numbers assigned to the subscribers by the telephone company. The contacts 2l22 of the group of one hundred lines would appear in consecutive order in the banks of connectors adapted to connect with them. The 15 contacts 35'36- 37 adapted to be selected by the line selectors however, may be arranged in groups having no reference to the subscribers number, and a distributing board of any-of the well known types may at the line selectors to average up the loads on the difierent groups of line selectors, as may be required in the operation. of an exchange. At K, I show the circuits of a line selector which is permanently linked to the circuits .of a first selector, C. The wipers 38-e 39-40 of the line selectors have preferably, as indicated in Fig.3, one hundred sets of contacts, each set consisting of a private contact and the line contacts lit-37. 'lhe onehundred contact sets are preferably arranged in ten groups of ten each, thewipers 383940 being adapted to first make vertical step-by-step move- :ments to select a group, and then rotary step-by-step movements to select, a contact set of agroup; Each group of horizontally disposed contact sets has a group contact 41 over whichtheauxiliary wiper 42 is adaptt ed, to Wipe, thevertical movements of the {line selector-being governed by the aux- Y iliary wiper 42, which passing over the group a contacts 41,-teststhem successively, the Wipers 38, 39,40 partaking of the vertical move- "ments. Whenthe auxiliary wiper 42 has group contact 4l,in an altered abnormal electric condition indicating that a line of the group is calling, the vertical movements are discontinued and the wipers 38-3940 automatically begin their rotary movements i selecting the particular contact set of the group belonging to the calling line, and resting in engagement with these contacts as soon as they are found. By this means, fanv line selector, of which ten maybe provided for the group of one hundred lines,

is enabled after being initially started by' the removal of the receiver at a substation, to automatically proceed and select the individual contacts of the calling line' whose eleotricalcondition will have been changed by apparatusrontrolled by the'removal of of the receiver. us a first selector C is the group.

brought the control of the calling not required. The first selector includes the wipers 737475,' corresponding to the wipers 38-39l0 of Figs. 2 and 3, and one hundred sets of multiple contacts 7677 78 of trunk circuits such as D. which contacts are arranged in horizontally disposed groups of ten contact sets each, each level or group of contact sets being assigned for connection to a difi'erent thousand of the ten thousand line exchange. The wipers 73-7l-75 are first lifted in response to directive impulses controlled at the substation at be conveniently employed for changing the group relations of the contacts of the lines -conta0t sets belonging to the wanted t ousand, and are then automatically rotated over the contacts of the group, the wiper 7 3 cooperating with the private contacts 176 of the trunks l) to select the first idle trunk of The trunk circuit D includes a rotary switch diagrammatically shown as provided with the wiper 94, the grounded disk 94 and the wipers 96 and 98. In the operation of the switch, the. wipers 94.-96 98 and disk 94 have a step-by-step rotary movement imparted to them and move over i the respective sets of contacts -97-99.

Each set of contacts 95979.9 pertains to trunk selectors E of a different one hundred group of called lines. nectors F for each hundred, and hence ten Y trunk selectors E, the trunk-circuit D is provided with ten multiple private contacts 101, connected to a contact 95 of the trunk-circuit, one of these contacts 101 appearing at each of the ten trunk selectors for the second one hundred. The trunk-circuit D also ;has. ten private multiple contacts 101 connected to the first contact 95, one-of these ten contacts 101 appearing at each of the trunk selectors pertaining to the first hundred of the thousand and the said trunkcircuit D has corresponding sets of ten privatecontacts connected to a contact 95 for.

each of the other hundreds of the thousand. At D the disk 94:- is sho wn in itsnormal position grounding each of the contacts 95,

The first clock-wise step brings wiper 94, upon the first contact 95, the second step -upon the second contact 95,, and so on. When the proper contact 95 has been see- Assuming ten con- In the' operation of the lected, movement of the switch ceases and the ground connection is removed from the wiper 94, thus rendering the private multiples of trunk-circuit l) in the banks of the trunk selectors pertaining to the connectors of a particular hundred, selectable in character by said trunk selectors. Simultaneously with the removal of ground from the wiper 91, the circuit connections of wipers 90-08, which meanwhile have been placed in connection with contacts 97 -99 corresponding to the hundred whose contact 05 has been engaged by wiper 9-1 are altered, and with the removal of ground from said contact 01, current is caused to flow. from wipers 00 and 98 to the contacts 07 and '1!) engaged by them to start an idle trunk selector switch E to select its multiple of contact- 101, and to operate the group 1ela v 100 to render the group contact of the subgroup, in which the selected twink-circuit 1) has its multiples, selectable in character. The trunk selector 1) may be similar in operation to the line selector shown at Fig. 2, its wiper 107 corresponding in function to wiper "-112 of the line selector and its wipers 101-105-100 correspond iiig in function to wipers 38-39-40 of the line selector. The contacts 102-103 of the trunkcircuit 1) are multipled to each trunk selecting switch E of the one thousand which the circuit D serves. .\Ve thus have the trunk-circuit I) having its main conductors connected to contacts 102-103 multipled one hundred times and having ten groups of ten private contacts each, one group including ten contacts, 101, the second group including ten contacts 101 etc., not multipled to all the switches containing multiple con .icts 102-103, but the private. contacts are groupwise, or as it might be expressed, distrilmtively'multipled among the one hundred switches havin the multiple contacts 102-103.

A connector F may be mechanically similar to the line selector, although the group contacts 41 and their auxiliary wiper 4; are not employed. The wipers 150, 151 and 152 of the connector are capable of being'adjusted vertically to select. a ten-line group,

of lines out of its humlred, and of being then rotated to select the contacts of the particular line wanted out of the group, the contacts of the one hundred lines served by a connector being arranged according to their tens values, in horizontally disposed groups,

in the usual manner.

1n the circuit structure of Fig. 1, the usual rel sase nn'gnet for each switch is omitted, as I provide a mechanical structure such that I am enabled to restore the switch to zero or normal position without a special magnet for this purpose. This is accomplished by causing, when the restoration of the switch is to be secured, the rotary magnet to elfect additional step-by-step movements of the wipers in the same direct-ion as those caused in the original'operation of the switch, until the switch wipers pass beyond the last contact set at the right of the bank, when the wipers may descend by gravity to their normal level and may .then be automltically rotated in a reverse direction back to their normal positions. As I do not employ the so-called sideswitch magnet in connection with the system of my invention, I use altogether but two magnets for each switch, one

being a lifting'or vertical magnet, theother 'being a turning or rotary magnet, and I thus that the subscriber, whose substation is shown at A, desires to have his line connected with that of the subscriber whose substation is shownat H, and whose number may be assumed to be 0251. In establishing the connection, the subscriber at A first -r.e-' moves his receiver from the hook-lever, whereupon hook-lever 1 disengages contact 12 and engages contact 11, completing a circuit from battery B, resistance 33, normal contact 32, limb L. contact 18, contact 11-1, contact 10, limb L, normal contact 28, line relay 23 to ground, operating the said relay whose attracted armature 21 disconnects private contacts 20 at the connectors from battery B via the winding of cut-off relay 2?, in order that the line of the calling subscriber may test busy to incoming calls, as will be more fully explained hereinafter. The attraction of armature 25 completes circuit from ground through the common group relay. 3-1 to battery, operating the said relay, whose attracted armature removes the normal ground connection from the group contact =11, it being assumed that the multiple contacts of the line of the. calling subscriber A appear in the first levels of the first line selector K. eleventh contact is preferably provided, as shown, for the aux iliary wiper 42, permanently grounded in order to insure a proper locking of the, primary relay PR of the line selector. The attraction of armature 26 of line relay 23 removes ground from the individual multiple private contact 35 of the calling line, and its multiples, to render them selectable; and the said armature 26 by engaging its alterlay wit,

assessegenerator G through primary magnet PN,

Each impulse, transmitised by the generai-or through said magnet, causes the switch short, carrying Wipers 38, 39, i and 2, to he raised a step; and such impulses will con tinue to flow as long as relay PR continues energized o current flowing from battery, through said relay, its attracted right armarure, and to ground through successive contacts ifi i-l to ground through she normal contacts of group relays inasmuch, however, as in the present case the calling line is in she low-cs level of contacts, the firsf step of vriper d2 brings it to engage a conta a $1, open at the armature of the first group relax T 3%; the locl-zing circuii throu Y PR is opened and its armatures "racred' as soon as one current in pulse 1 assed through primary magnet Lo oft ftle Wipers one step Vertical off-normal switch VGN was sh fted on she first vertical step of the Wipers to engage its alterneie Contact, which shifting would cause she starting of the sec- 0nd line selector assigned to the one hundred line group among which the line of A is included, were it not for the fact that reivnen operated as described, locked itself over circuit extending from ba ctery, through the relay Winding, normal "outact 5T, airernate ccnsacr to ground at rotary oi'l'-normal spring thus holding open the circuie of he alternate contact or" spring VON as contact &6; the two other branch cricuits of said alternate contact being open respeciively as arrna'zure 56 of relay RR and or she nrroa cureof relay 53. energize lion relay also attracicd ,ormasures l7 and 513 so respectively their springs as and :31, clien causing she said springs so discng: go their normal contacts. Current 4 vs from the positive pole of hart-cry ry relay PR, normal contact- 61,

%T, noriui ccnnact"55, closed normalcoutoci", 62 secondary relay a negai'ive lmlziery, oper'aiing the rec and The attraction of urinal-u. J oi seormdary relay closed a coutac: in circuit of the secondary or rotary i order i-l'mf, is may he oper l with generator as soon as, he dee'nergiza on ofrclay PR as descr. 1 she m'rnut-urc of said relay engages 12s normal contact. When, shoreoue portioneneeuding.

, PR and 27, operates relay 2?, and its armafore, the relay PR became denergized, im-

pulses begin flowing from generator G, nornial Contact of armature of relay PR, closed contact 50, magnet SM to ground, and said magnet, by its mechanical connections, turns 70 Wipers 38, 39 and in a rotary direction, a step for each impulse received by it. WVith the first rotary step, rotary oil-normal spring RON is shifted from its normal positionshown to engage its alternate contact, and the locking circuit for relay SR is extended to wipe:- 38 and to successive multiple contacts 35, armatures 30, normal contacts 26 to ground, until Wiper 38 reaches the contact 35 of a calling line assumed to be that of A, at which time the locking circuit of relay SR will he opened at normal contact 26 of relay 23 of the line of A, because the said relay is operated; and secondary relay SR will be deenergized and its armatures retracted, the retraction of opening the circuit of secondary magnet SM and preventing further rotation of the Wipers, Wipers 38, 39 and 40 are then resting in engagement with contacts, 35, 36 and 37' of the calling line; and on the retraction of armatures 47 and 52 of relay SR, the relays PR and SR will be held operated over new circuits (established before the former ones are broken by the makebefore break arrangements of springs 48 and 51) extending from battery B through relay PR, contact 61?, normal contact 48, contact 39-3G, normal contact 29, relay 27 to battery B, for relay PR"; and from battery B* through relay SR, normal contact 62 normal contact 51,'c0ntact 40-37, line limo L, contact 111, line limb L", and armature 28 throu'gh relay 23 to ground. The circuit before traced, including relays iure 28 engages its alternate contact, establishing a new circuit for relays PR and SR, holding them continuously energized, the circuit of relay SR now extending through alternate contact 28 and relay PR to positive battery, the armature 28 having a makebefore-break contact for the purpose. The operation of armature 28 also opensthe circuit of relay 23; armature 30 engages its alternate contact 29, causing the same to disengage its normal Contact, and comc pistes a locking circuit for relay 27, extending from battery B, through said relay 27, through contact 29-30, contact 35-38, normal contact 4,), relay L0 53 to ground, operating the relay 53, whose attracted armature completes a connection from theaiternaee contact of vertical ofi'? normal spring V'GN to the vertical offnormal spring VON of the'second line selector pertaining to the same group of one hundred lines including thereof A. This other line selector however, not operated at; ihis time because relay 23 is denergized and its armature 26 retracted. If, however, another calling subscriber were now to remote his receiver. .the resulting attraction of armature 26 of his lines relay 23 would complete a circuit from ground through contact 31 of his cut-oii relay to the common off-normal tion. on the first step, will shift its off-normal spring V03 to its alternate position; and as soon as it has completed its selection of the calling line, the third line selector will be operatively connected with the line relavsli-lot' the group of. subscribers lines via T n the shifted vertical off-normal springs ON" of the two operated line selectors, and so on in series through the ten switches serving the hundred line group. The vertical oil'- noi'mal switch springs VON and VON of switch .K were shifted on the first vertical movement of the switch, their functions being in connection with the release operations hereafter described.

The subscriber at A now rotates dial 17 from left to right until six teeth have passed below spring 19 and releases it. The arrangement of tooth 16 of the dial to spring 13 is such that when the dial is in other than normal position, the said spring 13 will rest in engagement with contacts 14 aiid 15; and during the manual rotation of thedial. the relays PR and SR at switch 0 are held energized over circuits extending from the two sides of battery B to ground through contact 1314. except whenthe circuits of the relays are interrupted by the teeth of dial 17 operating on springs 19 and 18, as here after described. ()n the release of the dial, its associated spring rotates in a reverse clockwise direction. the six teeth, which have been passed below spring 19, operating upon the said spring to cause six interruptions in the circuit of magnet PR, causing its armatures to be 'eleased and attracted six times; while relay SR continues operated via contact 13 14. After the last iiiterruption of normal contact 19 and the reenergization of relay PR following thereon, the single tooth at the lcffltif dial 17 (shown just below spring 18) causes the spring 18 to disengage its contact momentarily; and as the dial reachesfiiorinal. as shown, and contact 18 is again closed, spring 13 disengages its contacts 14 and 15 and the relays PR and SR are then again held energized over the metallic circuit of the line. There being ten teeth on dial 17 adapted to operate upon spring 19 as described; the calling subscriber may, in successive operations of the dial, effect a series of breaks at contact 19 corresponding to the digits from one to nine and corresponding to the digit zero, which latter will be represented by .ten breaks. The series of breaks repre-- senting any digit will, in each case, be succeeded by a single break of contact 18 and the opening of contacts 14, 15 and 16. It will be noted in the operation of the dial that, when the circuit of relay PR is being interrupted and the relay deenergized and energized. the relay SR is held operated;-

and that. when the circuit of relay SR is interrupted and its armature retracted and attracted. the relay PR is held energized,-

the arrangement at the substation being such that at no time are the two relays deenergized simultaneously in the operation of the calling device 17. The simultaneous deenergization of the two relays is only caused when the receiver is replaced upon the hook, the arrangement of the circuit at C being such that a SlllllllttlllQOtlS deenergization of the two relays is effective to cause the restoration of the switches. It will be noted,

however. that to render the calling device 17 effective. a coin must 'prior toits operation,

have been deposited in the slot 8 of the paystation device slioiviiassociated with the substation A, because unless this is done,

the operation of spring 19 will be ineffective I to cause the deenergization of primary'relay PR, since a circuit will he continued therefor to ground from liinh L, through normal contact 10 and contact 15-1413. Similarly. unless a coin is deposited in'the calling device, .the operation of dial 17 upon spring 18 will be ineffective to cause a dea, circuit foe-said" relay will be continued from limb L. through noriual contact 9 to ground via contact 13-14. To render his calling device effective. therefore. the cal ing/subscriber must deposit" a coin in the that itwill serve to support a deposited coin. The coin deposited will thus he supported and willflpress outwardly the springs 9 and 10, shifting them to their alternate positions by,it'scngageinent with the buffers of iiisulating material upon the-said springs.

"lhe resulting opening of norniai contacts 9 and 10 renders the dial 1'7 operatively effective as described. while the shifting of spring 9 to engage its alternate c ntact, bridges the winding of the polarized relay,

energizat-ion of secondary relay SR, because 4. across the springs 19 and 18 so that it.

is operatively related to the line limbs L and L when springs 18 and 19 are at normal. The relay 4 is polarized and the curarmature of the polarized relay 4 to be tilted downwardly. Such operation will have no efiect upon the arm ,3, and the deposited coin.

rent, flowing from battery B in the metallic circuit of the line and through the polarized relay 4, is at all times in one direction,

or of .one polarity up to the time the called;

Subscriber answers the callnamely, of such. direction 6r polarity as to tend to cause the will not be collected unless the called subscnber answers, when a reverse fiow of our;

. rentwill be caused in the calling line to opcrate the paystation device to collect the coin, .as hereafter describedfllf the calling subscriber, at 'sany time prior to the response of the called subscriber, replaces his receiver, arm 2 tilts arm 3 to normal andthe deposited coin descends through orifice 7 and is returned to the subscriber, the subscriber being required to pay for such calls only as are completed and'to which responses are made. f

Each of the six retract-ions of armature A 65 of relay PR causes a current flow from ground at 4:5, through alternate contact of spring RON, normal contact 65, rotary oil"- normal contact RUN, primary magnet PM to battery. The primary magnet is energized and de nergized siX times and is cited tive to liftjwipers 73, 74 and 75 six steps in a vertical direction, upv to the sixth horizontal group of contact sets which group is connected to link-circuits D, assigned for connection to the sixth one thousand group of subscribers in the exchange, those num- 'bered from 6000 to 6999. Simultaneously with the first vertical step of the wipers, vertical off-normal springs VON VON and VON were shifted. When the single break-in the circuit of relay SR is caused with the return of dial 1'? to normal, armature 66 of said relay is retracted to close idle circuit 1), contacts 76 ofxbusy circuits being characterized by ground connections,

while contact 76 of an idle circuit is on o en circuit. The deenergization of relay BR, qccurring when wiper 73 engages the contact 76 on open circuit, allows the retraction of,

its armatures, of which 70 operatively connects wi er 73, now engaging the multi lo contact 6- of the selected l nk-circuit with its alternate contact, which contact. is always connected to ground at 64 through; armature 63 of relay PR, or to ground" through armature 87 of relay SR, since one or both of these relays are continuously held operated, as before indicated, unt l the switches are restored to normal. Thus contact 76 and its multiples of the idle trunkcircuit from ground at 45, spring RON, normal contact 66, rotary offmormal spring RON, vertical cit-normal springs VON and VON busy relay BR to battery, oper- 4 ating the said relay BR, whose attracted armatures -69 and 72 disconnect wipers 74 and 75 in order that they may be on opentacts 77'fl11d 78 in existing armature of relay BR operatively connectsiits winding with wiper 73, which, en-' gagin successive contacts 76 of busy cirzcuits will hold the relay BR locked until the wiper 73 reaches the contact ,76 of an switches circuit D are connected through a circuit of practically no resistance to ground and are rendered busy -to any other first selector C whose wiper 73 maybe brought to engage a, multiple of contact 76 because in such,

case the operated relay BR'of the other'first selector will continue energized and its wipers 7 3, 74,? 5, will pass over the contacts of switch to test the contacts of the next switch of the group. Rotary off-normal springs RQN and RON were shifted with the first rotary movement of the wipers to disconnect magnets PM and BE from con-- tacts 65 and 66. The subscriber at A now operates dial 17 to cause breaks at contact 19 corresponding to the second digit of the called subscribefls number-that? is, two

breaks-wliich will be f ollowed by a break-- at contact'18; The said two brea at contact 19 efi'ect two successive deenergizations of relay PR, whose -armature 65 transmits two current impulses from ground 45 through shifted spring RON, contact 65,

contact 69,- contact 7i77, normal contact 90, contact 84, magnet M of switch D to battery B. Disk 94 and wipers 94, 96 and 98 are, by the resulting actuations of magnet M, turned in a clockwise direction, .two steps, wipers e4, 96 and 98 then engaging contacts 95, 97 and 99 respectively, associated with-the sets of multiples, 101, 102, 103', appearing paired withcon'nectors assigned for connections to the second hundred group at each of ten trun selecting I of lines of the sixth thousand, while disk 9t continues ground to the sets of multiple contacts 101, etc; pertaining to the other contacts 95' and associated wi the trunk selec g switches E, paired wi connectors F o the nine other hundreds of the said sixththousand. Rotarypfinormal springs RON", BON RONi, RON and'lRQN are all shifted to their alternate positions onthe first movement of the switch at D.

The momentary deenergization of relay SR, caused hy the opening of contact 18,

causes an impulse of current .tofiow from e5" through spring ROI l, normal.

eontact- 66, contact 72, contact 75-78, norinal contact 93, shifted spring RON relay 79 to battery, B, operating the said relay 79, whose attracted armature 83 immediately locks saidrelay to ground through normal contact of armature 87 of relay 86. It will be observed that upto this time wiper 9a was connected to ground through normal contacts 81 and 89, so that the multiple contacts 101 have remained grounded, which is their normal condition. \Vith theoperation of relay 79, however, armature 81 was atswitch of D, group relay 100 to battery B,

the group relay then attracting its armature to remove ground from the group contacts 108 with .which it is associated, at the trunk selector switches to enable the trunk selector (to be started as hereafter described) to select the group or level of contacts including those of the link-circuit D, into connection with which the-calling line A has been brought. The attraction of armature of.

relay 79 completed a circuit from ground through armature 92 of relay 86, attracted armature 85, contact 9899, over the'common conductor a, through vertical ofl"normal spring VON at the connector F, returning over conductor 1), vertical offnormal spring VON at switch E; the circuit then branching, one branch extending through contact 109, relay PR to battery, the, other branch extending through contact 110, relay SR to battery. 133;; current traversing the above-traced pathsTtlie -two relays PR and SR are operated, attracted' armature 1110f the former connecting its relays winding with auxiliary wiper 107, While armature 112 completes a-circuit from generator G through alternate c0ntact l12,,normal contact 121 and primary nnughetflVIf, which is now effective. under the influence ofuin'i-v pulses transmitted by generator G to raise 'wipers 104, 105 and 106 step-by-step until primary relay PR becomes deenergized. As

long as wiper 107 is passing over group contacts 108 pertaining to groups of circuits such as'D which do not include a calling circuit, such contacts 108 Will be grounded at theharniatures of the group relays because such relays will be unoperated. Thus relay PR will continue locked; but as soon as wiper 107 engages the group contact 108 associatedwith link circuit I) of Fig. 1, relay PR will become deene'rgized because its group relay 100 is operated. Armatures 111 and 112 will be retracted; and by the retraction of tho lull-er, generator G will be con-' lay SR continuing locked by current from 7.

battery B through the relay winding. normal contact 118, alternate contact 11%, wiper 101 and successive .contacts101 of idle linkcircuits D, through their respective disks 91". As soon, however, as wipers 10.1. and 106 reach the contacts 101, 102 and 103 of the calling link-circuit D of Fig. 1, the circuit of relay SR will be open at attracted armature 81 of relay 79; the relay SR will become deenergized and its armature 115 8 will fall back, opening the circuit of secondary magnet SM and preventing its further operation, the wipers of switch E then resting in engagement with multiple contacts of link-circuit D of Fig. 1. After the' in'tial energization of relay SR until the denergization of relay PR ,-tl1e said relay SR was locked to ground at the normal contact of rotary off-normal spring RON, which was shifted with the first ro cuit adapted tobethereafter coi'npleted ex- 1' tending from starting conductor 7) through vertical off-normal spring VON of the next trunk selector assigned to the group of link- I circuits D including the one shown in Fig. 1. During the operation of the switch E, 1 this circuit was, howe vgr, open at the armature of relay 1235f switch E, and a second trunk selector'E could not be started in response to the operation of another link-circuit Duntil the first trunk selector E had completed its operation as described. As soon, however, as, on the completion of the operation of the switch E of Fig. 1, armature 113 of relay SR engaged its normal contact, a circuit was completed, operating relay 123 whose attracted armature then placed the starting conductor 6 in conduc-. tive relation with the vertical off-normal spring VON" of the second trunk selector of the group. Should this second trunk selector be operated responsive to the operation of another trmik-circuit D, the shifting of the vertical off-normal spring VON of the second trunk selector, and the operation of its relay 123, on the coinplction ot the operations of the said second switch, would, in a similar manner to that just described, connect starting conductor b operatively with vertical elf-normal spring VON of the third trunk selector E of the group; and by similar operations of succeeding trunk selectors, the starting conductor 1) may be continued on through a series of vertical oft-normal contacts VON to any of the ten trunk selectors assigned to the one hundred trunk-circuits including the trunk-circuit D of'Fig. 1. The circuit operating relay 123 may be traced as follows: from battery through the. relay windin through armature 113 of secondary relay SR and through vertical off-normal spring VON to ground. \Vith the retraction of armature 116 of relay SR a circuit is completed from the normally grounded vertical off-normal spring VON at connector F, over the lower strand of the talking circuit indicated by the heavily marked line, contact 116, contact -106103, normal contact 80 and relay 86, to battery B, operating the said relay S6, whose attracted armature 91 engages spring 80, thereafter breaking the normal contact of said spring, whereby the relay 86 is locked to ground at rotary offnormal spring RON. Armature 87 unlocks relay 79 whose armatures are retracted, and armature. 92 of relay 86 removes the ground from wiper 98, this occurring before the armature of relay 123 operatively engages its contact in order that a. starting current flow may not reach the vertical off-normal spring VON of the second trunk selector when the trunk selector E of Fig. 1 stops. Armature 81 of relay-79 being now retracted, and armature 89 of relay 86 being attracted, a connection is completed from wiper 94 through said armatures 81 and 89, contact 76-73, normal contact of armature 70. to ground at 64 or at armature 67; and since the said wiper 91 of the switch of D is engaging its contact 95 connected to the private contacts 101, the said contacts 101 are again rendered busy to the trunk selecting switches, other than the one then engaging them, having access to them. Armature 93 of relay 86, in leaving its normal contact, ope 'atively disconnects relay 79 from armature 66 of relay SR at first selector C, and extends the circuit of said armature 66 through the alternate contact of armature 93 and contact 103106 to the circuits of the connector A. Armature 90 of relay 86 maintains magnet M disconnected from contact 77, and retracted. armature S2 of relay 79 deiinergizes the group relay 100.

The subscriber at A-now operates the dial 17 to cause five breaks in the circuit of relay PR whose armature is retracted and attracted five times to transmit five current impulses from ground 45 through armature 65), contact 7477, contact 102-105, arma.

ture 113, normal contact of armature 129 of relay 128, normal contact of armature 127 of relay 124, through primary magnet PM of the connector to battery B operating the said magnet PM five times and causing five vertical steps of the wipers 150, 151 and 152 of the connector F, bringing them horizontal with levels of contact sets including those of subscribers lines numbered from 6251 to 6250, followed by the contact set of subscriber 6250, the zero being represented by ten impulses.

A single break, caused by the calling device in the circuit of relay SR as the device returns to normal, transmits a single current impulse'by the retracted and attracted armature 66 from ground at -15, through contact 72, contact T5-78, attracted armature 93, contact 103-406, contact 116, through vertical cit-normal spring VON", shifted on the first vertical step of the connector F to engage its alternate contact, through normal contact of spring 126, relay 121 to battery. The said relay 121 attracts its armaturcs 125 and 127, the latter shifting the connection of armature 129 of relay 128 from the winding of primary magnet PM to the winding of secondary magnet SM, while armature 125 engages spring 126, thereafter breaking the normal connection of said spring, whereby the relay 121 is locked over a circuit extending from battery 13*, the winding of relay 124, contact 126-125, and vertical olf-normal spring VON of the connector to ground, it being understood that all the vertical off-normal springs VON, VON, VOA and VON were shifted with the first vertical step of the switch. The shifting of spring VO1\ to engage its alternate contact operatively connected the common starting conductor 0- of the ten trunk selectoi-s..E-of the group with conductor c extending to thewertical off-normal spring VON of the second trunk selector E: the shifting of the spring VON disconnecting the armature of relay 123 from the conductor a, the circuit heretofore traced through said armature being substantially an emergency circuit only. being of utility in case the calling subscriber, after having secured the connection of his line through to a trunk selector E and its connector should fail to transmit further impulses, in which case the connector would of course re main at normal; and vertical off-normal spring VON ren'iaining uushifted, other subscribers would, except for the relay 123, have no access to the other trunk selectors E. Phe subscriber at A now operates his dial 1? tocause four breaks in the circuit of j relay 128 being then locked by current flow- .to battery B operating the said magnet four times, which is eifectiveto rotate wipers through 150, 151 and 152four-- steps to engage the fourth contact sets of the selected levels,

which will be contacts forming'multiple terminals of subscribers line number 6251, or

- the line of H. .A single break in the circuit of spring VON, now shifted; thence to rotary off-normal spring RON, shifted withthe' .firstrotary movement of the wipers of the.

connector F, through the normal contact of spring 130 and through relay 128 to battery fB operating the saidrelay whose armature 131 engages spring 130, thereafter opening the normal contact of said spring, the

ing through'contact130-131,.vertical oflnormal spring VON- to ground. The at- ,tracted armature 133 of relay 128 oper- .ativel TR t rough the left-hand armflature' of reconnects the winding lot test relay lease relay RR and its normal}: contact and through attracted armature with the testing wiper 150 of the connector. then engaging the private contact 20 of the called line. It being assumed, first, that the called line :is idle, current will then flow from -ground 'at test relay TR, over the before- .traced connection, through contact 150-20,

normal contact 21 of line'relay 23 of the calledline, through its cut ofi' relay 27 to battery'B", operating test relay TR'fJtnd cutoff-.Irelay 27. The former'attracts it?) armatures, of which 147 immediately shtxrt circuitsa portion of the relays winding, substantially reducing the resistance of the cir cui traced. The armatures of relay TR continue attracted bu t any other relay TR of ianother connector that may be brought in multiple with the shortcircuited winding will not receive enough current to operate it, as hereafter more ully explained. Armature 146 of the test 1' lay is attracted, which preizents the interrilper I,'now operativcly conriected with th n-rma1 contact of said armature 146 via attracted armature 132 of relay 128, from' transmitting to the calling subscriber a busy signal; while armatures 144 and 148 close normally open contacts in the two strands'of the talking circuit, indicated by the heavily marked conductors. Armatures 28 and 32 of the now operated cut-oif; .relay 27 disconnect the limbs L and L of the called subscribers line from their normal iljconnections to the two sides of battery B; armature 31 opens a contact in the starting conductor ofthe line circuit of the called subscriber H; while armature 30,- in engaging its contact 29, completes a branch connection from ground at armature 147 of test relay TR to multiple PllX'fitB con tacts 35 at the banks of the lin selectors associated with the called line, in order that 'anyline selector that may be started may,

ed armature 145 now'completes a circuit from battery B". through ringing relay 14:9, said armature 145, normal Contact of armature 139 of relay 137 to ground through the constantly operatingginterrupter I. The inclusion' of said interrupter in circuit causes 5 the relay 149 to alternately attractand release its armatures, including and excluding ringing generator G from circuitwlth the called subscribers line, the generator current passing through contacts 151 21 and 15222, over limbs L and L of the called line, condenser and call-bell at the substation via contact 121 tbereat. causing the bell to icing. The called subscriber, in answer to the signal, removes his receiver from the hook-lever, which then disengages contact and engages contact 11, completing a circuit as follows: from battery B, through relay 141. through contact 144, upper armature of ringing relay 149. when retracted, contact 15121; limb L, contact 15), contact 111,, the substation transmitter supplying talking current thereto, contact 18, limb L, contact 22-152, retractcd lowcr armature of rclay 14 attracted a rmatnre 1-18 through relay 142 to the opposite pole .of battery B, the two relays 141 and 142 being thereby operated and current being supplied through the impedanccs of these relays to the called line for talking purposes. The attracted armature of relay 141 closes a contact in the upper strand of the talking circuit, while the lower armature of relay 142 closes a contact in the lower strand of the talking circuit. The upper armature of relay 142 is attracted to close a circuit through relay 137 to battery, which relay 137 locks itself through attracted armature 140 to ground at shifted vertical off-normal spring VON".

Armature 139 of said rclay opens acontact in the circuit of relay 14$), preventing its further operation. armature of relay 141 alsocompletcs a circuit from the positive pole of the battery 13, to the left over the upper strand of the talking circuit, through contacts 102,5

7774, attracted armature 65, through reversing relay 60 to the negative pole of bat-5 tcry, operating the said relay 60, which, by its make-before-break armature combinationf reverses the connections of the two poles of, battery B to the line conductors LL ofg the calling subscribers line, the make-beforebreak combination, referred to, preventing- 'lhe attraction of the this occurs. the buffers upon the denergization of relays PR and SR while the connections are being shifted. The current now flowing over the calling subscribers line is in the reverse direction to that 'ireviously flowing thereover. A portion of it passes over limb L, through llOOlilever 1. contact 11. through the transmitter returning over limb L. while the remainder flows in a branch path at the substation through the windings of polarized magnet 4. alternate contact 3). contact 18. returning over limb L. This current through magnet i tilts its armature 5 upward. which armature engaging the spring screwed to the arm tilts the upper extremity of the said pivoted arm to the left. so that the. coin deposited in coin slide 8 is free to descend by gravity through orifice 6 and be collected. \Vhen springs 9 and 10 are no longer pressed apart by the coin and they return to a normal position. spring 9 opening the circuit of magnet short-circuits from limbs L and L respectively being then established via normal contact 9 and 10 respectively. to contacts 18 and 15). so that the coin collecting mechanism does not in any way affect the flow of current through the substation. The two subscribers, A and H. are now in conversation. the talking circuit being traced from substation A through the exchange mechanism of Fig. 1 by the heavily marked conductors and to substation H by limbs L andL.

When the called subscriber replaces his receiver after conclusion of conversation his act is effective to restore tlle eonnectg, l to normal. hen the subscriber A vplaces his receiver. his act is effective to restore switches K. C, I) and E to normal. To trace in detail the release of the connector when H replaces his receiver, the restoration of his hook-lever 1 opens the conductive circuit 'of his substation and relay 142 is deiincrgized.

The retraction of the upper armature of relay 142 closes a circuit from battery B throngs; release relay RR", attracted armature 138. retracted armature of relay 142. attracted armature 140 of relay 137 to ground at vertical off-normal spring VON", the relay RR thereupon locking itself by the attraction of armature 135 to ground at said spring VON". Attracted armature 136 of relay RR completes a circuit from ground through constantly operating interrupter I closed contact 136. alternate contact 129, alternate contact 127, and secondary magnet SM to battery B". The interrupter I now causes current pulsations to be transmitted through magnet SM which is effective to rotate wipers 150151-152 additional steps from left to right until the wipers pass beyond the right edge of their contact banks shown in Fig. 3. When this occurs. the shaft of the switch and the wipers descend by gravity tothe normal horizontal I level, when the spring included in the switch mal spring RON of the connector F will be restored. The restoration of V0)? opens the locking circuits of relays 124128, RR and 1357 which relays then allow their armatures to be retracted. It may be observed at this time that when relay HR was oper-. ated. the attraction of its left armature maintained open the circuit of test relay TR so that it was decnergized as soon as the release began. and its armatures retracted. wipers 15U151l52 of the connector being all on open circuit while they were wiping over the contacts during the release. The shifting to normal of vertical olf-normal spring VON operatively connects starting conductor a of the trunk selecting switches E with conductor 7/. but the said conductor would be open at the armature 121 so that other subscribers would be prevented from starting the other trunk selectors l). were it not for the fact that relay 12 3 is operated. It will be observed that on the energization of releaserelay RR. its armature 131i opens-the circuit of relay 141 causing its dei nergization. When the calling subscriber replaces his receiver. the conductive disuniting of the line limbs at the calling station. caused thereby. effects the dci nergization of two relays PR and SR and current flows from ground at release relay RR of line selector K. through said relay RR. through the normal contactof the spring of relay SR. through the normal contact of armature 33 of relay PR through vertical )fl'-i1()i'i1i:il spring VUN' to battery B through the protective resistance shown. the relay RH locking itself by its attracted armature 58 via off-normal springs VUNat from ground to shifted verti 'al ofl' normal spring VON. said attracted armature 57 and secondary relay SR to battery B. The secondary relay then attracts its armatures of which armature 50 completes a circuit for secondary magnet SM which is thereon operated by impulses transmitted by generator G until the switch wipers 3839l0 pass beyond the right edge of their banks when they descend b v gravity and are turned back to normal by the associated spring. The attractions 'of armatures .47 and place wipers 39 and 40 on open circuit, but the attractions of said armatures do not cause relays PR and SR to be operated as was the case when relay SR was energized when the switch K was making its selection, because at the present time contact 55 of relay RR is open. lVith the attraction of armaat The attracted armature 57 of release relay RR completes a circuit said switch has been restored.

tracted, but a circuit extending from the common starting conductor of the line group, connected to vertical off-normal spring I switch was being restored via attracted armature 56 to the vertical oft-normal spring VON of the first idle switch of the group of line selectors. When the line selector reaches normal, vertical off-normal springs VON, VON, and VON are restored to normal, the shifting of VON opening circuit through secondary relay SR and allowing the retraction of its arm'atures, VON opening a contact in the locking circuit of release relay RR which, however, will continue o erated through vertical oft-normal spring ON of the first selectormnless the Spring VON in engaging, its normal contacts operatively'connects the windings of secondary relay SR and primary relay PR with the common conductor connected to the said spring. Rotary oft-normal spring RON was shifted to normal on restoration of the switch to disconnect ground from the normal switch contacts of armatures and 66. .When relay RR was first operated it completed a circuit from ground through attracted armature 59, shifted off-normal spring VON, busy relay BR .of the first selector to battery B which relay attracted its armatures (39 and 72 to place wipers 74 and 75 on open circuit while the switch O was wiping over contact sets 76, 77, 78 to reach the right edge of its bank in order to be restored, armature 71 being attracted to--.

complete a circuit for secondary magnet SM to effect the required rotation. The vertical and rotary off-normal springs are shifted to normal when G is restored.

It will be observed that the continued operation of secondary magnet SM to bring the switch wipers free of theircontact banks, is dependent on the continued energization of busy relayv BR, which latter depends upon the continued attraction of armature 59 of release relay RR. To take care of the contingency that the line selector K may reach normal before the firstselector O, the locking circuit of relay BR of the linev selector is carried through the vertical off-normal contact VON of the first selector, so that relay RR is only deenergized when both the line selector and the first selector have reached normal.

When the armatures of relays PR and SR, were retracted before relay BR had time to'be operated, acircuit was closed from battery '13 through 'vertical ,ofinormal spring VON, through the normal armature combinations of lrelays, PR and SR, normal contact '70, contact VON was continued while the' lay . relays RR .was established through spring RON? at tracted armature 89 of relay 86, normal con with magnet M to cause a continued rotation of the switch D. by said magnet in the direction in which it was initially operated around to its zero or starting point, at which time the rotary ofi-normal springs -RON2, RON=, RON, RON5 and RON will be shifted to disengage their contacts, spring RON deenergizing release relay RR while spring RON opens a contact in the circuit of the magnet M, preventing further operation thereof. The shifting of springRON" opens the locking circuit of relay 86 and the relay then becomes deenergized inasmuch as switch E will, by the time the switch of cir-' cuit Dis restored, have had its wipers 104- 105-106 moved out of engagement with the multiple contacts 'of circuit D. It may be observed that while the switch of circuit D is being rotated around to normal, the ground upon contact 101 and its multiples is traced through armature contact 81, alternate armature contact 89, rotary oft-normal spring RON and to ground through the winding ofrelease relay RR.

It will be observed that while the first selector is having its wipers rotated to free the bank, the wiper 7 3 will-be. connected to battery B through the resistance of busy' re- BR. While thus connected, wiper 73 may pass over multiple contacts 7 6 of trunkcircuits D which may be in use and hence have their release relays RR" placed via their 'rotaryoff-normal springs RON'- in circuit with battery Bthrough relay BR. Such however, will not receive current to operate them, their windings being shunt- PR and SR, connected through normal contact 70 and wiper 73to-contact 76, a

branch path of the path operatingrelay RR tact 81, wiper 94, contact connected to multiple contacts 101,? contact 101-v104, normal contact 114, release relay RR to ground,

ed by branch circuits practically devoid of operating the said relay RR whose ittracted armature 119 thereupon locked the, relay to battery normal spring VON, while armature 118 in engaging its alternate-contact completed a ath for current from ground through. shifted vertical off-normal spring VON, at

tracted armature 118, secondary relay SE to battery B, Relay SR is thus operated, its armatures 113 and 116 place line wipers 105-406 on open circuit while the switch is being rotated until its wipers pass beyond the right edge of toeir banks responsive to current impulses flowing from generator G through normal contact 112, attracted armature 115 and secondary magnet 3M lVhen the switch is fully restored, vertical ofi-normal springs VON, VOlland (9N are restored, denergizing the various relays held operated during the restoration of the switch, and rotary oil-normal spring RON is also restored. While the switch E is being restored to normal, armature 120 holds closed a contact in the circuit of starting conductor extending to the vertical oil-normal spring ON, through the next idle selector E of the group in order that it may be operatively associated with the other circuits to which it is assigned. If at the time, the callin j subscriber A replaces his receiver to initiate the release operation described as being caused by him,'th-e called subscriber H has not answered, the closing of contact 1253 resulting on the energization of relay RR completes a circuit from ground through the operated contact 122, normal contact 138 ofrelay 137 through .re lease relay atthe'connector F which relay will cause the release and restoration of the connector in a manner similar to that before described.

Having now traced the operation ofthe system in completing a call and restor ng its central otfice mechanism to normal in the case where thecalling line was found idle, I will now describe the manner in which the connector. F is enabled to test the called line, it being assumed to be bus and in such case to cause the transmission of a busy signal to the calling subscriber.

Let it be assumed that the line of H is busy because some connector other than F of Fig. 1 has been caused'by a calling subscriber to be placed in connection with multiple contacts 2-il-2i22 connected to those lotll5llo; or the connector F of Fig. 1. In such case, the circuit holding energized the test relay of th eriously connected onnector traced from ground at armature 2.4. of relay TB of the said connector through a portion only of ll" winding and through the cutoll' relay 2 of the busy called line to battery B T relay TR oi the conntlctor of Fig. l is, by the before (lQSClllOQLl operation of armature 1 33 of relay 128, placed in connection with the test contact 150, the relay TR of the connector of l ig. 1 will remain unoperated because its enl'lie winding is at this time included in a branch of the circuit already existing which includes only a portion or" hus, uhcn the the winding of the test relay TR of the prea busy signal is transmitted from interrupter 1 through attracted armature 182, normal contact of armature 146, armature of relay 141 to the left, over the upper talking conductor of the exchange indic'ated'by the heavily marked conductor through condenser 682 normal contact of spring 61, thence following the upper talking (3011'- ductor through contact l1'1 at the sub station and the primary winding of the induction coil, causing an audible signal in the substation receiver, returning over line limb L and the lower talking conductor through the exchange, through normal con tact 62:", condenser 38 over the lower talking conductor, through the lower normal armature contact of relay 142 and to ground through condenser 143. The calling subscriber being thus advised that the called line is busy, replaces his receiver causing simultaneous deenergizations of relays PR and SB and all the switches including the connector are restored to zero as in the case where the calling subscriber was assumed to have replaced his receiver before the called subscriber answered, all as heretofore desc 'ibe Inasmuch as relay 141 is not operated in the case when the called-for line is found busy, the reversing relay at the first selector C is not operated and a reversed flow of current was not caused in the calling subscribers line to operate the polarized magnet l to raise its armature 5. Hence the coin deposited in coin-slide 8 is not col lected and when the calling subscriber replaces his receiver, the arm 2 of hook-lever 1 is efiective to tilt the arm 3 to the right allowing the deposited coin to descend through orifice 7 and be returned to the calling subscriber.

Let it be assumed that the line of H is busy as a calling line at the time subscriber fa attempted to place the line in connection therewith. If at that time the line has not already been selected by a line selector, its contact 20 will be on open circuit at armature 24 because line relay 23 will be then operated, and the test relay TB of the corn motor of Fig. 1 will necessarily remain inert and the bus signal will be transmitted as before described. If the said line of H is busy as a calling line and another line sedied sets of contact pairs through cut-ofi" relay 27 of contact 20, the said line.

a call should he change his mind and not .into )1: when 46 l y lector like K has selected the said line, current will. be flowing froml battery B the said line, through closedcontact 29'30 to private contact 35 at the line selector, through wiper 38 of, the line selector connected with the line, which is similar to that at K, through relay'53 thereof to ground. In this case, when relay TB of the testing connector of Fig. 1 has its circuit completed through 'to the wiper 150 in engagement with multiple relay TR will be placed in a branch circuit of the circuit just traced, extending to the common point at spring 29, and the test relay will in such case be shunted by the relay 53 of the line selector. The test relay will in such case remain inert, not receiving enough current to cause it to attract its armatures although the relay 53 will continue to receive enough current to holdits armature attracted] The calling subscriber in such case will receive the busy signal in the manner before indicated, and in replacing his receiver, will. cause all the ,switches to be restored to zero."

It will be' remembered that when the call-, ing subscriber replaces his receiver first, the resultin simultaneous deenergizations of relays PI? and SR areifective to cause the restorations of whatever.switches may have been.operatively connected with his He is thus able, after starting to make desire to complete it, to restore whatever switches have been operatively connected with his line bythe replacing of his receiver. I. have shown at E" an overrun switch OR ada ted to have its contact closed, as indicate in Fig. 2 by the top of ratchet 170, when the switch shaft is stepped an eleventh step, .when the overrun switch will close an opening circuit of relay RR to release switch E. 'The overrun switch will come wishing to complete his call, hangs up his receiver while the trunk selector-is making vertical steps.

It will be understood that batteries B and B may be a single source of current,

and that the batteries indicated at B, B and B may be another single source. I

Referring now to Figs. 2 and 3, showing a two-dimension line selector mechanism adapted to erform the mechanical functions require of the circuit at K of Fig. 1, a main frame 174' is provided to which the above and below, the

shaft S is journaled vertical and rotary ratchets 170 and 173' 'be- Fastened to the' ing attached to the shaft. shaft S, "are also the wipers 38, 39 and 40 and the auxiliary wiper 42. -The contact b'anks, of which'a front view is includedin Fig. 3, are suitablysupportedby the mainframe, an upper bank comprising -one hun- 36-37,. arranged mary or lifting "pivoted, adagt ll, the;teeth of ratchet ,170-,' the against b'ack the shaft against return rotary the calling subscriber, n'otin ten horizontal groups of ten pairs each, the wipers 39 and10'being "adapted to be raised upward to select a horizontal group, when the wiper 38 willbe movedla corresponding degree to be placed-oppositethe corresponding group of private c'ontacts35,

of which one hundred are provided in the lower bank, arrangedln tengroujps often For lifting shaft S=and its wipers; he prlmagnet PM is-proy (led, to 168 a suitable pawl 169 ised to engage, with aetuatio'ns of magnet P retaining pawl 175' engaging successive, teeth of ratchet 170 as the shaft is lifted step-by-step by pawl 169 't'o -1hold it'- movement. For rotating; the shaft. and wipers, a secondary'mag net SM is provided, 'supportedby-the t'r'ame' 174, having .a driving pawl-172 carried by" its armature 171, adapted, with the'act'uations of the magnet, to engage teeth of-the ratchet. 1 73 to rotate the shaft and ".w-ipersa. A retaining pawl 176 is fn-ovided, normally engaging the base of ratchet 170, -.wl iich.=has p a smooth surface so that pawl l'zfi' is filf-" f elfectiveto prevent the return movement-of .the shaft when the shaftis at its normal level. Withthe first upward step-"of the shaft, however,

the ratchet 173 is larou ghtf into operative relation with ,pawl 176*;rirn'd I when the shaft'is turned under tliefzihflirg ence of magnet SM, the'said pawl 1f76-en gages successive .teeth of ratchet 1T3, tohold 'nuivement'. i Clamped to the upper portion of shaft i is an arm 160 shown in Fig. 2 as extending to the left an?! having a downwardly bent portion normally engaging a spring ii) v Yith the firstupward step of the shaft, the 1 said arm 160 d sengages spring'V.\vl1-iclr1s then free to move in its tens1on..- The vei tlcal off-normal switch springs shown in Fig. 1, VQN, VON and VON, are 'counected by studs .of insulating material to spring V, as indicated'in F g. 4,..so that all of them will be simultaneouslyshifted to. their alternate positions on the first step upward of'shaft S. Fitted loosely about the Fig. 5) in order that it'may rotatedwith the shaft, is the arm 161, normally engaging the rotary off-normal spring RON. as shown ,in Figs. 2 and 5, and adapted, with the'lilst 

